DESCRIPTION: (Adapted from the applicant's description) The long-term goal of this project is to dissect out the mechanisms which govern the release of follicle-stimulating hormone (FSH). The recent studies utilizing sheep as a model has provided compelling evidence that: 1) FSH secretion is episodic; 2) each gonadotropin releasing hormone (GnRH) pulse is associated with an FSH pulse; 3) GnRH-independent episodes of FSH occur; 4) Factor(s) present in the hypophyseal-pituitary portal blood can selectively regulate FSH secretion; and 5) the FSH-releasing activity in the hypophyseal portal blood is not due to activin. In this proposal the researchers will determine 1) the biochemical nature of the FSH-releasing activity; and 2) whether FSH-releasing factors with similar chemical characteristics such as those present in the hypothalamic portal blood can be obtained from hypothalamic extracts.